1. Field of the Invention
The present invention relates to a scanning module and the method thereof, and more particularly, to a scanning module that is capable of integrating optical paths of illuminating and imaging into one optical path for size reduction, and improving the quality of scanned image by using optical polarizers for filtering such that is capable of further achieving the same effect as the “projection scanning” digital camera.
2. Description of the Prior Art
E-society is coming vigorously and rapidly following the development of science and technologies. From the computer and electronics expositions within the past five years, one can clearly perceive that the electronic products with newer technologies, lower prices, and convenience in usage are commonplace. As a result, the development of the E-society is expedited.
Because of the revolutionary development in the electronics technology, almost everybody are able to operate those electronic devices easily, thus, the standard of living has reached to a very high level in the recent years. Taking image processing for example, two popular means are currently used, i.e. by using digital cameras and by using scanners, and are respectively applied in different applications.
However, there is still room for improvement in both the size and power consumption of a conventional scanner. Please refer to FIG. 1A, which is a 3-D schematic drawing of a scanning module according to the prior art. A scanner 11 composes: a body 15, an optical chassis 12, a document window glass 13, two guiding rods 14, a power supply 16, and a cover 17. The optical chassis 12 is a bar type module having therein a linear light source 121. The power of the optical chassis 12 is supplied by the power supply 16 such that the optical chassis 12 move along the direction of the guiding rod 14 so as to perform an image scanning process on a manuscript (not shown) arranged on the document window glass 13. The cover 17 is used to cover the document window glass 13 during the scanning process for fixing the scanning manuscript and preventing the background light from entering into the scanning area such that the clarity and contrast of scanning are deteriorated. Please refer to FIG. 1B, which is a side view of FIG. 1A. As seen, an optical path is formed starting from a light of the light source 121 arranged inside the optical chassis 12 is directed on a manuscript on the document window glass 13, and the light is then reflected back to the optical chassis 12 passing successively through a first mirror 151, a second mirror 153, and a third mirror 155, and then finally is fed into a CCD 159 through a lens 157. The optical chassis 12 must move from the left to the right to scan the manuscript. According to the above description, due to the fact that the optical chassis 12 in the prior art has a shape of a cuboid and the CCD 159 is a “linear” imaging module, the optical chassis 12 having therein the CCD 159 needs to be moved from the most left to the most right of the document window glass 13 in order to acquire the entire image. In this regard, the body 15 will require more space therein. Moreover, the length of the light source 121 (typically a fluorescent tube) has to match the width of the document window glass 13. A light source 121 that is overly long not only takes up space but also consumes more power.
In the optical path shown in FIG. 1B, because of the imperfect design in the optical shielding, a portion of the light emitted from the light source 121 can enter the CCD 159 and mix with the reflected light of image, which will affect the quality of the outputted image. Therefore, how to filter out the unwanted light in order to get a purified light will be another important subject addressed in present invention.
Besides, since the conventional scanners all have a design with a fix optical length, meaning that the positioning of mirrors, lens, and CCD are all fixed, only documents with specific size such as A4, A3, etc., can be scanned, furthermore, the documents have to be able to be placed on the document window glass 13 such that a scanning process can proceed. The scanners of prior arts are not capable of performing scanning utilizing the technique of variable focal length (i.e. varying the length of the optical path). Based on the current techniques of the scanners and the design of the optical components, to design an optical path that can vary in focal length in order to achieve the “projection scanning” similar to a digital camera is another important subject of the present invention.